Abstract
Sera from 30 patients with community‐acquired, biopsy‐proven chronic non‐A, non‐B hepatitis (NANBH) were tested for antibodies to the C100 protein of hepatitis C virus (HCV). The 20 patients who showed reactivity in this assay were followed prospectively for 6 months, during which time seven were treated with recombinant α‐interferon. HCV RNA was detected by “nested” polymerase chain reaction (PCR) in 19 of the 20 anti‐C100‐positive sera taken at the onset of the study and also in five of the ten anti‐Cl00‐negative sera. Pretreatment viraemia levels ranged from 2 × 10^3^ to 2 × 10^8^HCV genomesiml. After 6 months of interferon, elevated serum alanine aminotransferase (ALT) levels had fallen to normal in four of the seven treated patients. In each case the response to interferon was accompanied by either a disappearance of or a decline (1 log to 8 log reduction) in viraemia. HCV genome titres in the three nonresponders and in the 13 untreated anti‐C100‐positive patients did not change significantly over this 6 month period. These findings confirm the aetiological role of HCV in community‐acquired NANBH and suggest that quantitative PCR will become a valuable technique for monitoring the antiviral effect of interferon and other experimental treatments.